I thought the real reason was because the puppeteers didn't want the kids to see the strings on the marionettes and spoil the illusion. But no.

The real reason?

"It's something I came up with after an incident in the early '70s, when a little boy started to climb up on top of the puppet stage," says Lewis Mahlmann, director of the Puppet Theater from 1967 until he semi-retired (accent on the "semi") in 2004.

"He had one leg over the front, and he was about to fall 6 feet into the pit behind the stage. We rushed outside and caught him just before he fell."

The next day, the Magic Pink Line made its first appearance.

Like the late Mr. Rogers, Mahlmann is a moralist at heart.

"I do puppet shows to entertain, but not just to entertain," he says. "I want to show them there are wonderful stories out that they can read, and I also want to teach them the right way to live."

For instance, in the puppet production of "Pinocchio" (which bears little resemblance to the Disney version), Pinocchio doesn't achieve his dream of being a real boy until he learns to be kind to others.

The Blue Fairy says to him, "If I give you a wish, would you rather be a real boy?"

He replies, "I'd rather my father get well."

And at the end of the play, when Pinocchio doesn't recognize his friend, the cricket, after he turns into a boy, the cricket turns to the audience and says, "Maybe there's somebody else out there who needs me."

Heavy stuff for a 5- or 6-year-old, but Mahlmann makes the message go down easier with a constant barrage of jokes and puns that keep the little ones screaming with laughter.

And he thinks children are capable of understanding a lot more than we give them credit for.

"One thing I never do is talk down to a child," he says. "That may sound phony, but it's true. I'll tailor the language to their learning level, but that's not the same thing."

Every kid loves puppets, but a few get absolutely hooked and decide to become puppeteers themselves when they grow up. Mahlmann has always taken them under his wing and taught them everything he could.

One of them was a 10-year-old boy named Randal Metz, who shyly knocked on the door of the Puppet Theater one day in 1970. And except for a couple of stints studying with the Muppets, he's been there ever since.

Two years ago, he succeeded Mahlmann as Puppet Director. Mahlmann pays him the ultimate compliment: "He loves puppetry as deeply as I do."

The Puppet Theater is observing its 50th anniversary this month. To celebrate, Fairyland is building a new stage that, if not quite state-of-the-art, is still a lot better than the old one.

"They've built a ceiling over the stage, so now I have a grid I can fly the scenery from," says Mahlmann. "I've always wanted to have that."

Everyone at Fairyland wanted to name the new stage after Mahlmann. But, ever modest, he vetoed the idea.

"That would be too egotistical," he says. "I think 'Children's Fairyland Storybook Puppet Theater' is a fine name."